Deposition of Functionally Graded Material Fabricated by Robot Plasma Arc Welding

Abstract

Functionally graded materials (FGMs) are a new type of composite materials capable of facilitating the dependable bonding of dissimilar materials. A double‐wire plasma welding process is used to manufacture Stainless steel 316 L (SS316L)/Inconel 625 FGM. Subsequently, two thin‐walled structures with 5% gradient and non‐gradient are fabricated to investigate the morphology, microstructure, and properties in different gradients, focusing on the 67% SS316L region. In the findings, it is indicated that two depositions exhibit well‐formed structures with varying gradients and no macroscopic defects. The composition experiences an abrupt transition at the interface between depositions with a non‐gradient, whereas deposition with a 5% gradient does not exhibit this issue and demonstrates a higher effective deposition rate. The analysis of the energy dispersive spectrum indicates the presence of Nb elements at the grain boundary in the 67% SS316L region, with no observed cracks. This suggests resistance to cracking and impediment to the segregation of Nb. Additionally, the hardness and tensile strength in various regions exhibit a gradual increase with a 5% gradient of Inconel 625 content, while the tensile anisotropy is not noticeable. Consequently, the 5% gradient transition demonstrates a more favorable performance in comparison to the non‐gradient sample, resulting in the avoidance of the 75% SS316L region due to its poor performance.